Rhizoma Drynariae is the rhizome of Drynaria fortunei (Kunze) J. Sm or D. baronii (Chist) Diels, which is used for the treatment of bone fracture for a long time (Zhong Yao Da Ci Dian (Lexicon of Traditional Chinese Medicine), 1658–1660, Shanghai People's Press, ShangHai, 1979). Ma Ke-Chang et al., studied the influence of Rhizoma Drynariae on rat Osteoporosis model, the results showed that Rhizoma Drynariae extract partically restrains the glucocorticoid-induced bone loss (Ma Ke-Chang et al., Zhong Yi Zheng Gu (Bone Setting) 1992, 4, 3), but the active component therein is unknown. Additionally, Zhou Tong-Shui et al. reported that the effective component of Rhizoma Drynariae for treating bone injury is naringin and analogues thereof (Zhou Tong-Shui, et. al., Zhong Cao Yao (Chinese Herbal Medicine) 1994, 25, 249). And they also performed assaying in crude plant of Rhizoma Drynariae (Zhou Tong-shui et al., Zhong Guo Yao Ke Da Xue Xue Bao (Journal of China Pharmaceutical University), 1996, 27, (9), 540), but they didn't show the relationship between the above-mentioned active components and the effect to Osteoporosis thereof.
Wu Ying-Pi et al. disclosed a method of extracting naringin from Citrus grandis Osbeck var. tomentosa Hort, aiming to obtain the single component of naringin (Wu Ying-Pi et al., Zhong Cao Yao, 1988, 19, 452) only. Therefore, it is unknown whether or not such method can be fitted for other medicinal materials.